New South Wales in autumn 2015: Severe weather in coastal NSW

Several East Coast Lows cause severe coastal weather

Below average rainfall in southern and western NSW

Close to average temperatures

The statewide average rainfall for NSW was 7% below average during autumn, with average to below average rainfall across much of inland and southern NSW but well above average totals in the Sydney, Hunter, and New England regions. A major feature of the season was a cluster of several east coast lows, which brought heavy rain to southeast NSW on April 8, the Sydney and Hunter regions on April 20-22, and the north coast on May 2. The event in mid-April was particularly severe, the most damaging east coast low since June 2007. It caused strong winds, high seas, coastal erosion, and prolonged power outages. Major flooding was observed in the Williams and Patersons Rivers, with severe flash flooding in Dungog. Severe thunderstorms also affected several areas during March, with a storm on 7 March causing hail of over 7 cm in diameter at Narrabri, resulting in widespread crop damage.

Both maximum (+0.2 °C) and minimum (+0.4 °C) temperatures were close to average for the state as a whole, with generally warmer than average temperatures in the northeast and cooler than average temperatures in the southwest. The season started with very warm temperatures during March, with a notable late-season heatwave. This was followed by below average temperatures during April, which was the coolest for maximum temperatures since 1999, with several stations recording record-low April temperatures on the 20th and 21st. However, persistently warm sea surface temperatures contributed to the warmest autumn for Lord Howe Island in over 20 years.

Notes

A Seasonal Climate Summary is prepared to list the main features of the weather in New South Wales using the most timely and accurate information available on the date of publication; it will generally not be updated. Later information, including data that has had greater opportunity for quality control, will be presented in the Monthly Weather Review, usually published in the fourth week of the month.

A Climate Summary is generally published on the first working day of each month.

This statement has been prepared based on information available at
11 am on Monday 1 June 2015.
Some checks have been made on the data, but it is possible that results will change
as new information becomes available.

Averages for individual sites are long-term means based on observations from
all available years of record, which vary widely from site to site.
They are not shown for sites with less than 10 years of record, as they cannot then be calculated reliably.
The median
is sometimes more representative than the
mean
of long-term average rain.

The Rank indicates how rainfall this time compares with the climate record for the site,
based on the
decile ranking
(very low rainfall is in decile 1, low in decile 2 or 3,
average in decile 4 to 7, high in decile 8 or 9
and very high is in decile 10).
The Fraction of average shows how much rain has fallen this time as a
percentage of the long-term mean.